1. Technical Field of the Invention
The present invention relates to a heat exchanger. More particularly, the present invention relates to a heat exchanger preferably applied to, for example, a gas cooler or evaporator provided in a supercritical refrigerating cycle device.
2. Description of the Related Art
A conventional heat exchanger is disclosed, for example, in Japanese Unexamined Utility Model Publication No. 2-109185. This Japanese Unexamined Utility Model Publication No. 2-109185 relates to a heat exchanger in which a plurality of tubes 110 are connected between two header tanks 140. As shown in FIG. 16, this heat exchanger is composed as follows. The header tank 140 is composed of a tank section 150 and plate section 160. In the plate section 160, there is provided a tube insertion hole 161. In the tank section 150, there is provided an inclined face 155 with which a tube end section 111a comes into contact. In this structure, size Lt, by which the tube 110 is inserted into the tank section 150, is made to be smaller than size Ls which is a size from the tube end section 111a to the tank ceiling section 153.
Due to the above structure, when the tube 110 is assembled to the header tank 140, the tube end section 111a comes into contact with the inclined face 155 of the tank section 150. Therefore, it is unnecessary to use an exclusive positioning jig. Further, it becomes unnecessary to conduct machining on the tube 110 to form a profile used for positioning. Further, when sizes Lt and Ls are determined so that an inequality Lt<Ls can be satisfied, the resistance of flow in the header tank 140 can be decreased and the cross-sectional area of the tank section 150 can be reduced.
However, even if the above structure is adopted, the tube end section 111a still protrudes into the header tank 140 by size Lt of insertion. This protruding tube end section 111a causes the resistance of flow when internal fluid flows in the header tank 140. Accordingly, a reduction in the cross-sectional area of the tank section 150 is naturally limited.